Method of producing a protected metal article



Oct. 2, 1956 2,764,808

METHOD OF PRODUCING A PROTECTED METAL ARTICLE A. w COFFMAN OriginalFiled June 4, 1949 IN V EN TOR.

my a .M mm mm 1% A TTORNEV United States Patent This invention relatesto a method of teeted metal article.

An object of the iflvehtibn i's te ia'rotide e hevel and imprdved methodof firodtieiiig iiid tetd irie'tal hftiels forming the suhjeetiri'tttter of thy Ur'iited States Pateht 2,073,334; da'ted Me reh 9, 1937, atid- 15y which superior proteeted metal ertieles may he predueed ineceriorhi'ca l, rapid arid efiieieht With this gehe'ral ehje'etifi viewa'fid stttfh e'tliers as may he're'ineifter appear, ihv'ehtieh eohst'stsiii the method of making the pitefd tfie'til ert ie' heteifiafterdescribed 3116 particularly defih'etl iii the eliiiis at the end "ofthis specifi'eatibn.

In the drawings, Fig. l is diagrammatic view iii side elevation of thepresent apfiar'afli's fer pre'dueih-g p'tdt'e'ted metal sheets; Fig. 2is a set'itiilhl detail of the firdfe'ted metal sheet produced by theapparatus of Fi l, and Fig. 3 is a detail in hem eleyatiohilltist-tatiiigthe the: ehai'i'isrn for trhhrhih-g' the edge ier-hens 6fthe firiwteted metal sheets: i

In general; the present invention seeks t6) prevlde im roved niethed ofproducing preteetetl metal ert iele of the tyifi disclosed in my patentahoye' r'fefrd to which coln'ptises metal with: 10, preferably ah irehor steel sheet having layers 12 of fibreus nitteril; ire? erably'asbstos p l'p'r or felt, securedto tit least @he and preferably re Bothdf the "opposite stitfaees therecsf by all preauelhg a preinterposedlayer of metal adhesive 14; The metal 36- hesive 14 preferabl completelyehveleps the metal sheet and may comprise a nen-eorredible' metl such aszinc; tin, cadmium, lead or ether HOlT-cbfiddih'l rhe'tal 6r alloy, andthe metal adhesive is ztlloyed to the rhetal sheet 10 and keyed oranchored to the fibers comprising the fibr 'ous; layer 12. In practice,-the' flbreus layers may he saturated with a suitable itnpre'gnahteemprisrfig preh erably ebitumirious c emposi-tioh; such as asphalterresinous material or the like, hr with a'n'y' df the other eommer'eialimptegharits which have b'eeh- 01* may be found suitable for use forimpregnating sueh fibreus layers, and if desired,- the pfotect'd metllarticle thus far described may be further protected by eh (l fl't'lweatherprcefing eoatin-g 16" which niay orhphise' any desiredc'ompositiori of bitumiii'olls 1"'r1aterittl, Wea'thetresisting iesins,or resinous edrnp'ositions and id pfaetiee, a bituh'iihoti's compositioninelu'dihg dottbnseed pitch and asphalt he's been found to pessessthedesired weather resis-tariee and du rability.

The apparatus aridfmethod for prdtrcing' protected metal sheetsillustrated inmy Patent No: 2,073,334; above referred to, and thecommercial process he'retofm e em ployed in the prdduetieni of suchp'rotect'ed metal sheets have contemplated the passageefi successivesteel sheets through a galvanizing bath; and as the sheets l'aye thebath they are eond ieted' upwardly between a pair of exit rolls and aretheir immediately conducted a direction substantially at right edges tothe direction at which the sheet left /es the bath. In other Words, asthe said patent.

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metal sheets leave the g'ahahizingheth they are passhig in e genera-1v'eitital direction arid the eeu'rse of travel of the sheets is tllfidefleetea to {e herizez'htal direetihr'i as the sheets pass Betvveh thehdfidirig rdll's by which the fihro'us la'yeis are rolled onto thegely'etiil'iing eeatin befdre the latter hais" heizme solidified asillilstitted iii Experiiie hts defndfistrhlted thtt method ofmanufa'ttiiing the pfdteted metal sheets intto'dii'ces seveiail difiiciilties, aild the resent invehtioii seeks am'oiig ether thingst'cijarovlde a method aiidtp paidths Whi-eiii these difhc'ultis they beavoided. The fdlldfi/ih'g indiates sofne (if these 'diffieiiltiefsBecause at the size and bulk or the bonding rdlls aiid other associatedequipment zirl'd supp'dltiing structure, it hid been found nee-essaryiii praetiee t6 lote the bond ing rolls seye'i al fe't aiivhy friiiiithe exit iolls of the galvetnizing bath, with the resiilt that niehinielguiding mechinisr'n had to he provided f'cii coildiictin the sheet fromthe galvanizing bath to the hehding' ro'l s, aftieit leirly is thedirection of ttaivel ef the tne'tzil sheets in passing ffcinl thegalvanizihg batli tethe bending rolls had to" be alteredsub'steiht'ially it wesr ehd thtt the gti'idiiig ihe'ehdni'siitseoi edthe Iinde'r'sid of the fieshly applied galvanized surface of t e sheetso that the the he zinc cdatiiig was abraded ttfid merited B'y eqntetetwith the guiding Inehafiis'm and as a fs'fllt the tl'riifdilnity of thezine cdatiiig en the uhdershijfeee 6f the steel sheet beihg" preeessedwas de's'trey'ed; This led; of unit mif'y' tended to produce ltck er'adlisidli Between the fib'rous sheet Add the undersurf ee of the steelsheet zit the fibiuts Where the iiitrkihg had ee'ehrred. H

Another ditfieu'lty exeeiieheed in' the firaletic'al esera' tioi'i ofthe afifi'ratus shown in p'atnt 'ahoiie' referred to, arose from thefact thtt the sli ht excess 6f zifi was rolled off the end of thegr'lyziliize sheet by the h'oiidirig mils wh n the eiid of the sh'e'etreeehed the fiiii er he hills. This z'iiio Wes de iwb sited iii sihallintisss' lyjoh the adjacent suretee of the felt heihg fed ever the"lewer bending toll aiid heri'n'ted the felt Fayer' during the behciin'gd'per'atioii end fdtz'r'ied iii drape hpo'ii the surface of the feltlaiy'er thus headed ta the uhdersicle of the steel sheet,- in manyinstiiite's dro'pplhg down Ohio the fibrous ove'riiig which was iisutllyirsed to" eo' er the lower hdhdir'i'g roll. This talies p eee w ile thezinc is in a matte-her fit'iid Condition; eifid' ftei" ex'e'ss zirlowhich filldS its entry the lower roll and solidifies, it is then forced15y thf bonding rolls into the surreee at the su c'cdiiig written-s erthe fib'i dus' felt durin'g the eo'ht'ih'u d opefeitieh ef the separaes, r'uptu'ritig the felt and at the seihe time poi-rnar'kihg' thesurfziee or the lower horiding rol'l. "Cdritihued deems-eh ever t p'riod(if time produced stieh indentttiotis in the hehdingreils that pressureat the seeding rolls across the width of the reieeted metal sheets beingpreuueed it passed through the mending ren eeeeme he lenger unlifofiri;hilt was l'ocaliZe'd at the high phi-ms of the irregular surface of themills, "produclng eree' s di/ei' the surfte' of the irote'cted the't'all sheet where blistering eecuried dlie to the defective boiid'il igbecruse of the uneven presstires produced. Iii additidn, the depressedportiolisf'e'sultifig in the libriding' loll because of the 156K?iiiz't'rks", p'roduee'd areas of 10W tires re r'esuitihg ir'l blis=tering between the felt tiidthe g'lvtiiiiiihg (floating due to leek ofpreper hoildir'ig pressure at sueh points;

Another diflieulty elifieriefi'ced with the ftSregOin'g 815- aratus isthe produetidn at at; ih'e uahty 6f the derisit'y or trn'ourit of metalcoating, stitch as ghl'vth'izi'hg coeiti-rig, upon the bottom and top'sides of the steel sheet.- This results firimarily from the fact that asthe metal sheet leaves the coating bath its direction of travel isehngedabout 90 so that during the bonding er the fibrous sheets thereto themetal sheet assumes an are or a e'ur'yd creating the inequality of metalcoating, and in practice it has been found that the fibrous sheet uponthe upper surface of the completed sheet is always more uniformly bondedto the steel sheet than is the fibrous sheet secured to the lowersurface thereof. While the various operational difficulties above setforth detract to some extent from the most efficient operation of theapparatus referred to, nevertheless the apparatus has proven to becommercially operative and large quantities of the product producedthereby have been sold.

In accordance with the present invention, a more uniformly and moreperfectly bonded protected metal sheet of the character described may beproduced by disposing the bonding rolls above the galvanizing bath insubstantial alignment with the path of travel of the metal sheet as thelatter leaves the bath so that the sheet continues to travel insubstantially a straight path until. and during its passage through thebonding rolls. Preferably, the bonding rolls are disposed above thegalvanizing bath so that the metal sheet as it emerges from the bath,travels in a vertical direction. This enables any excess zinc on bothsurfaces of the sheet, as it is emerging from the bath, to run uniformlydown the sheet by gravity so that the coating weight may be controlledby the surface tension of the zinc itself and also permits this excesszinc to drop back into the galvanizing bath, thus preventing it fromfinding its way onto the bonding rolls. In addition, regulation of thetemperature of the galvanized coating upon the sheet between the timethat the sheet leaves the coating bath and the time that the bondingoperation is performed as the sheet travels between the bonding rolls,contributes to most efficient bonding.

The temperature of the coating of zinc upon the galvanized metal sheetduring the period of time the sheet is travelling from the point whereit emerges from the galvanizing bath to the point where it passesbetween the bonding rolls may be regulated in various ways. In thepreferred method and apparatus provision is made for adjusting thebonding rolls vertically to shorten or lengthen the distance of the samefrom the bath and in that way to maintain the temperature of the coatingof zinc upon the sheet at the point of bonding within a predeterminedrange. The temperature range at which bonding takes place may beelevated or lowered by shortening or length ening such distance as thecase may be. This adjustment of the bonding rolls toward and from thebath may be effected manually by mounting the rolls on vertical slidesand adjustably clamping the slides in different positions correspondingto the desired position of the rolls. In some instances I may prefer toprovide automatic mechanism controlled by the temperature of the coatingbath for automatically adjusting the vertical position of the bondingrolls. In some instances I may prefer to maintain the bonding rolls in afixed position and to utilize auxiliary heating means for providing acontrolled and heated atmosphere through which the coated metal sheetpasses as, it emerges from the bath in its travel to the bonding rolls.The control of the temperature of the coating upon the metal sheet atthe time that it is ready to pass through the bonding rolls plays animportant part in obtaining the most satisfactory bond between thefibrous material and the metal sheet, and in addition enables thethickness or weight of zinc coating on each side of the sheet to becarefully controlled to the end that the steel core sheet may besatisfactorily and most economically weatherproofed.

I prefer to employ one or more of the foregoing methods of controllingthe temperature of the metal adhesive coating on the sheet as describedin order that the continuous operation of the machine may not beinterrupted, stopped, or slowed down, in order to compensate for anyvariations occurring in the process. For example, when the apparatusembodies a galvanizing bath, if fresh zinc is added to the bath, quitenaturally the zinc bath will. drop somewhat in temperature. This drop intemperature of the bath may be rapidly offset by a movement of the rollscloser to the surface of the zinc coating bath. Likewise, if during theprocess a different gauge or strip steel or sheet steel were to beprocessed, the bonding rolls would be moved somewhat nearer or fartheraway from the bath, depending upon the heat balance which resulted inthe steel strip. i

It is a fact that during solidification of the molten zinc coating uponthe metal sheet, after passage of the sheet through the bath, thecoating passes through a so-called mushy stage due to the presence ofsmall impurities. For most effective results, the bonding operationshould take place at a temperature reasonably near, but above, thismushy stage. It has been found that the sheet steel of various gaugeswhen heated in the galvanizing bath at 850 F. and removed therefrom,have on their surface a liquid zinc coating which solidifies whenexposed to the air after varying lengths of time, depending upon thegauge of the steel. For example, 26-gauge steel so treated results onexposure to room temperature in a solidification of the zinc in tenseconds; whereas IS-gauge steel upon cooling under similar conditionsfor thirty seconds has a zinc surface which is solid. It can, therefore,be seen that a change of gauge, a change of air temperature surroundingthe steel strip coming from the galvanizing bath, fluctuations in thespeed of travel of the steel strip, and fluctuations in the temperatureof the galvanizing bath all have a distinct bearing on the relativelocation of the bonding rolls to the bath to assure the most efficientposition of the rolls at which the bonding operation should be carriedout. With properly designed bonding rolls which can be rapidly adjustedin height above the galvanizing bath, the problem of balancing all ofthese factors may be readily solved.

Referring to the drawing which illustrates a protected metal sheet andthe preferred apparatus for practicing the present invention, a coil 11of either hot or cold rolled steel strip may be operatively supported ina suitable standard, not shown, and from which an elongated strip ofsteel may be conducted into the galvanizing bath 13 contained within thegalvanizing tank or pot 15 or individual lengths or sheets of steel maybe fed by suitable feed rolls, not shown, into the galvanizing bath. Insome instances it may be desirable to feed individual sheets cut byshears 17 from the continuous coil of steel and in any event theindividual sheets or the continuous strip are passed under bottom rolls23 located below the level of the molten zinc, lead or other metal inthe bath and from which the sheets or strip are caused to emerge bydriven exit rolls 24 located above the bottom rolls 23 and preferablyarranged side by side so as to permit the coated steel sheet or strip toemerge in a vertical direction from the bath. The design, combinationand location of the various rolls for handling the steel sheets or stripin and from the bath may depend upon the type of galvanizing processused and particularly upon the presence or absence of a flux.

In the event that the galvanizing coating bath is operated with a flux,it is preferred to provide an exhaust system including hoods 30connected to an exhaust fan 32 for drawing off any fumes from the fluxor if desired, suitable shielding members 34 may be interposed betweenthe galvanizing bath 13 and the bonding rolls indicated generally at 25,in order to prevent the volatilizing flux from depositing excessively onthe galvanized sheet or upon the fibrous layers to be bonded thereto asin either case the deposited flux when contacting the hot coated steelprevents the most perfect adhesion of the fibrous felt to the steelresulting in a blistered product.

In accordance with the present invention, the bonding rolls 25 aroundwhich the asbestos felt or other fibrous layers are caused to pass fromsupply rolls 26, 27 thereof comprise steel rolls which are driven toadvance the sheet of steel passing therebetween, and in accordance withthe present invention are. arranged side by side in a subspreeosstantially horizontal position such as to permit the steel sheet afterit has left the exit rolls 24 from the .galvin-i-zifig bath 13 to passin a straight path and to avoid any sub= stantial deflection of thesteel strip until after it haspass'ed through the bonding rolls. Inpractice, and as illustrated herein, it is preferred to mount thebonding rolls together with the supply rolls 26, 27 upon a movablecarriage 40 by which the entire assembly may be bodily moved into aposition to one side of the exit rolls 24 leading from the galvanizingbath 13 to thus expose the entire galvanizing bath and to afford accessthereto. Preferably, the entire assembly is also mounted to permit it tobe moved vertically toward and from the galvanizing bath, and theseresults may be accomplished as herein shown by mounting the frameworkupon which the bonding rolls and associated parts are assembled, upontwo uprights 42, 44 to be elevated by hydraulic or other means and alsoto permit the entire assembly to be dropped down when such pressure iswithdrawn or lowered. As herein shown, the entire assembly is movablymounted upon rails 30 to permit the entire assembly to be movedlaterally as described.

During the withdrawal and travel of the asbestos felt layers from thesupply rolls 26, 27, it is necessary for best operation to preheat suchfelts in order to remove all moisture and also preferably most of thebinding and organic material in the felt. Such procedure is necessaryfirst to produce a moisture-free felt which will not blister when itcomes in contact with the coated steel, and secondly, to give a more orless porous felt which will be best suitable for saturation in thesuccessive steps of operation, as will be described. For this purposevarious types of heating devices may be employed, herein shown as aseries of gas burners 50, so located that the gas flame impinges on thesurfaces of the asbestos felt which are to come in immediate contactwith the zinc or similar coating upon the steel strip during the passageof the coated steel and felt between the bonding rolls 25. It isimportant that the gas burners be located to direct the flame in thismanner because if the heating were to be directed against the oppositeside of the felt, small quantities of volatile material would remain onthe surface of the asbestos felt which is to come in contact with thezinc or other coating and such a procedure would result in blisteringdue to the rapid volatilization of such constituents under the heatcontained in the coated steel.

In passing through the bonding rolls 25, the zinc coating on the steelis forced into the interstices of the asbestos felt and simultaneously,at least in part, solidifies due to removal of the heat from theassembly of felt and steel, and as the steel strip issues from the exitside of the bonding rolls, the asbestos felt is firmly attachedto thestrip of steel. In the bonding operation, it is desirable to employasbestos felt somewhat wider than the strip steel used, so as tocompensate for any slight lateral travel of the strip or of the asbestosfelt. Therefore, the assembly issuing from the bonding rolls has anexcess of felt extending beyond the lateral edges of the steel strip.This excess material must be removed from the strip, preferably beforethe strip is impregnated with asphalt or other impregnant. In order toaccomplish this removal, the sheet is carried up through the conveyorwhere the trimmer device 58 is installed. As herein shown, this deviceconsists of two grinding wheels 59, 60. The upper wheel 59 grinds offthe excess of the upper felt, and the bottom wheel grinds off the excessof the bottom felt. The springs 64 are adjusted in such a way that thegrinding wheels aways follows the strip edges even when the strip tendsto move in lateral directions. By creating V shapes on both edges of thepassing strip assembly the wheels hold the strip closed by the two bottoms of the VS and do not allow it to move in vertical direction. Thewheels may be made from regular Carborundum or from special steel andmay be of cylindrieel form as indicated. As the grinding operationcreates asbestos dust, an exhaust system is preferably provided toremove the dust to an accumulator. i

The trimming operation has to' remove not only the excess felt but alsothe excess. zine which is squeezed from the surfaces of the steel andaccumulates at the edges of the strip during the bonding process.Therefore, the trimming device should be installed near the bondingrolls in order to grind off the zinc excess when the zinc is not toohard but still in the more or less plastic state. After the trimming ofthe excess felt and zinc, the product is saturated in asphalt or otherwaterproofing impregnant.

As described in U; S; Patent No. 2,073,334, the satu rating operation ispreferably carried out in a single pass through a saturating tank 70.While such a, procedure results in a partial saturation of theasbestos-covered strip, the saturation is far from complete, and inorder to achieve complete s taturation, it has been found that theasbestos-covered strip must be passed through a saturating tank havingmore than one set of squeeze rolls 72. As indicated, the strip passesbeneath the surface of the liquid asphalt at (a) and then passes throughthe first set of squeeze rolls 72 which remove the excess of asphalt onthe surface of the asbestos-covered sheet, and then the sheet passesthrough a second clip at (b), followed by a second set of squeeze rolls74 which again remove a large part of the excess asphalt on the surfaceof the asbestos felt. A final pass through a set of hot rolls at 76smooths out and makes more uniform the entire appearance and surface ofthe saturated asbestos on the steel. By such a procedure, it has beenpossible to build up the saturation of the asbestos felt from about 25%to a maximum of about 40%. That is to say, the asbestos felt, bysuccessive dippings, in more or less completely saturated rather thanleft in a partially saturated condition. The problem of saturation ismore difficult than the saturation of ordinary felt since, in thesaturation of felt, the saturation takes place from both sides of thefelt surface, whereas in this procedure all saturation must be from oneside of the felt only, since a metal sheet separates the two layers of:felt bonded to the surfaces of the steel. A further improvement in thesaturation process is that the saturating tank is mounted to be movable.Its location depends on the speed and gauge of the strip. Furthermore,due to its special shape, the level of the asphalt contained in the tankcan be regulated thus permitting the operator to regulate the saturationtime and obtaining a dry product. By these improvements, in the designof the saturating tank, the easy and quick adjustments of the saturatingprocess is achieved, and when the facors such as temperature of asphalt,distance from bonding rolls and level of asphalt are synchronized withthe gauge of the passing strip, the saturation process reachespractically the maximum of efficiency.

Subsequent to the saturating operation, the strip is permitted tocontinue its travel due to the action of the pinching rolls 80 to theshear where is: can be cut to the desirable lengths and loaded on thebuggy 86 or the strip may be conveyed to the recoiler machine 88 whichis equipped with a cut-off device 90 as used in standard practice andwhich is preceded by several idling rolls 92 to permit handling of thecontinuous passage of the strip through the complete line ofmanufacture. The abovedescribed operation results in the manufacture ofasbestos-protected strip in coil form in which the asbestos is saturatedwith asphalt or other suitable impregnating material. This product maythen be uncoiled, passed through a roller leveler, cut to length andprovided with a weatherprof coating as previously disclosed in U. S.Patent No. 2,073,334.

This application is a division of my application Serial No. 97,246,filed June 4, 1949.

Having thus described the invention, what is claimed 1. In a method forproducing a building sheet, the steps of passing a sheet of core metalthrough a bath of molten non-corrodible metal and upwardly out of saidbath in a substantially vertical straight-line direction-to carry asubstantial film of fiowable molten metal therewith on the surfaces ofsaid core sheet, moving said sheet in said direction, withoutsubstantial deviation therefrom, and simultaneously and continuouslydirecting and horizontally pressing asheet of fibrous material againsteach said surface of said core sheet and into said molten metal at apredetermined station along the vertical straightline path of travel ofsaid core sheet, and controlling the temperature of the coating ofmolten metal adhering to the core sheet to maintain it in a flowablecondition be tween said bath and said station whereby molten metalsqueezed from said film by said sheet pressing step flows along saidfilm directly to said bath, along both sides of said metal core sheet.

2. In a method of producing a building sheet, the steps of passing asheet of core metal through a bath of molten non-corrodible metal andupwardly out of said bath in a substantially vertical straight linedirection, to carry a film of molten metal therewith on the surfaces ofsaid core sheet, moving said core sheet in said direction, withoutsubstantial deviation therefrom, simultaneously andcontinuouslydirecting and horizontally pressing a sheet of fibrous material againsteach of said surfaces of said core sheet and into said molten metal at apredetermined station along the vertical straight line path of travel ofsaid core sheet, and controlling the temperature of the atmospheresurrounding said path between said bath and said station to therebyregulate the temperature of said molten metal between said bath and saidstation.

References Cited in the file of this patent UNITED STATES PATENTS2,031,035 Dreymann Feb. 18, 1936 2,073,334 Cofiman Mar. 9, 19372,135,886 Elder Nov. 8, 1938 2,330,530 Tuttle Sept. 28, 1943 2,349,951 NFuller May 30, 1944 2,631,641 Coffman Mar. 17, 1953

